Masking method and apparatus



July 26, 1960 s. A. LoPENsKI MAsxING METHOD AND APPARATUS Filed Dec. 31, 1957 w w tv A mf 2,946,696' f Patented July 26, 1961) United States i Patent" @man i This inventionV relates generally' tro-the selective' treatment of articles. and, iny particular, to' a masking method` and apparatus forlshielding a selectedgporti'on of a cylin-` drical article such as a projection lamp bulbfrom' sprayed coating material. n'

During the. course of manufacturing certain'articles' it is' 'often necessary or desirable forv functional or purely decorative reasons to process O12 coat a particular part of thearticleor' are a"of"it's outer surface. In. the electric lamp industry, forl example, it. liasbecome the'standard practice Atovcoat, the top of 'a'projection lamp bulb with anA opaque layer of suitable' high-temperature material such, as ceramic paint or 'the like in"rde to prevent the leakage of stray/ light upwardly, through the projector housing.- Heretfor e,"this wasy accomplished-by shield'- ingfthe main body portion of theY bulb with a tight-tit-y ting'mask of rigid matcrialand'spr'aying the exposed top portion until a coating of the desired Aop'ac'ity V'was ob-,f

tained.- The utilization of a tight-ttingjnask of rigid' construction, however, was'inherentlyf impractical inas-v4 much as bulbs which werers'lig'htly oyersizecould not be inserted into the mask and those which were ,under-size.y

were not eiciently shielded, kthe latter' condition resulting in a smeared or uneven line ,of demarcation between -the body portion of 'an article found that when spray coating the end of an article, suclrVVV as the' topgof ra tubular lamp bulb, the desired neatly-I de'ne'd cut-offs would only be obtained if the gas flowing.' out of the shield were maintained at a velocity greater" than that of the impinging particles. This requirement, in conjunction with the fact that when coating the top of the bulb the spray was of necessity aimed in such` a direction as to oppose the gaseous outow, rendered this mode of masking rather critical. Thus, if the guny were placed too close to the bulb or the pressureof the air supplied to the gun or shield were improperly controlled; or balanced, then some of the sprayed particles would penetrate the gaseous barrier and enterthe shield result-"-Y ing in a ragged cut-orf line or graduated frosted effect thereat, which effect is commonly referred to as feathering. These defects, while they did not impair in the least: the utility of the coating, were undesirable from an appearance standpoint. It is accordingly the general object of the present invention to provide a method and means for selectively treating an article with a pressure-applied'medium with#H out deleteriously affecting the quality of the finished product or complicating the processing operation. i i Y Another and more specific object of the invention is to provide a convenient and inexpensive `method of masking,Y Y from sprayed particles so thatio'nly a selected'end portion is processed and a'shar'p';

accurately-oriented line` of cut-off is produced thereon@A that. is substantially even and free ofy featheringf Still'ano'ther object of the invention is Ythe provisionof'v masking' apparatus which, while inherently trouble-free the coated and uncoatedareasor so-called cut-01T line operationof both bulb and 'mas o, y

. In an attempt toovercome this problem themasks v were made slightly oversize and lined'with sponge rubber or the like ,inr order to compensate `for thevariatio1is in theY which necessitated atime-consu'ming and costly cleaning'v bulb, dimensions and thus maintain thev intimatek surface.

contactV necessaryto eifectivelysealoff lthe area undery thefmask' from` theA sprayed particles. masks v of this character tof withstand thehigh ambient,

temperatures required to set andlcurethe.coatingandA Atheir inherentshort life necessitated Vthe, frequent insp'ec tion and Vconditioningor replacement thereofin orderto. a insure coatings of acceptable,.quality.thus.rendering this..k manner ofy masking', i not only,-impractical .ffrom,both a v.

quality ,control .andf cost o standpoint,butunsuitableffor ,use l in high-speed bulb coating'equipment. f

In the`V copending.applicationj Serial. No. 5706,/l3,6-of- I. Petro entitled,` Masking-.Method and Appa1.2 1tus, which application is iiled-V concurrently herewith-fand as# signed to the instant assigneefthereaisfdisclosedpand;A claimed an improved masking-,technique and'rneanswhich.v

obviate the foregoing deciencies of therprorfartstruc tures by utilizing, incombination'; withfa rigid loose-iitf tingshield,v ail'ow of pressurized g'as1inthespaceabetweenl the shieldv andv articleto sealonifthey enclosed-f-.po'rtionzfo'f'fv said article fromY the processing mediuml'. The' gaseous: 1 outflow from the shielding memberisfthus employe'dfas the-.protective agent rather thanL-theintirnate 'surface'.con# tact of the. shield with thearticleiaslhretoforef -Whilc`f this' arrangement affords' distinctSv advantages over-1 th prionartl `practices,particularly `with fregard? lto' thei du#VV rability oflfthe: apparatus andgth'ef'easegofl'eading; inf-Wasi 1 cessed' portion and effectthe inal regioncof iinalcut-od,

and capable of withstanding,high-temperature conditions with a minimum of maintenance and replacement of parts,

will consistently produce a' sharp neatly-dened cut-off'.

line at a' preselected part of an article despite variations. in the dimensionsk of said varticle and the manner in'which the processing medium' is applied.

The aforesaid'objects of the invention, and others which willbeco'me apparent as thedescription proceeds, arel achieved by inserting the partof the article to be pro-l tected into a loose-fitting shield in the manner disclosed' injtlieaforementioned copending application Serial No. 706,436 ofi '1. Petro and then manipulating the article. (or shield) so that the article Yis recessed within the shield a predetermined distance in excess of that required" to produce the desired cut-orf during that portion of the spraying cycle 'when' an iniiux of sprayed particles, isy most `likely to'occur. After the end of the article hask beenicoated, the spray gunris positioned abreast of or' slightly below the'edge offthe `shield and the article raisedj l thel aforesaid predetermined'distance tolexposeyth'e "re-'1 spray only during the final phase of the coatiugoperati' when'the'sprayed particles transversely impinge on the ar-. ticle-and can be easily deflected by' the shield td produce? acut-oif free from Vany fea'thering or raggedness. a

The presentinvention', therefore, constitutes an 'im-y provement over-the maskingarrangementdisclosed andi cl'tL'med in lthe *above-mentioned copendin'g applicati" t, Serial No. 706,436 of J. vPietro in that while'tthe4 sam structural components arefusedthe desired ei'hectv i ist; achieved by properly manipulatingthe various elements-f ratherr than by maintaining a carefully controlled How ofy pressurized gasfrom the shield. The underlyin'gjprin ciplefof this invention isi-.thus basically differentv yan provides amore practical-'solution to the' problem 10ft coating the-end of an article Withla` p're'ssure-appliedl essing medium since the shield and nottligase iio'vv'A3 tlie'reir'orn'v serves as the 1 primaryr protectiv orV asking means whi'clifl determines kthe location t 'cut-off." Thus,' thfe'" Y I soto speak, is;k exposed to the" utilized as an auxiliary protective agent to accelerate the setting up of the coating material and eliminate' the possibility that the backwash or overspray generated by the jet of atomized air may force particles into the shield,`

experience has shown that if the shield and articlev are properly manipulated with respect to each other and a soft spray pattern is employed acceptable coatings can be produced Without introducing a gas into the shield.

For a better understanding of the invention reference should be made to the accompanying drawing wherein: Fig. 1 is an elevational view mainly in sectionof a spray type bulb-coating -apparatus embodying the present invention and showing the line of movement of the spray gun with respect to the top of the loaded bulb during the i coating operation;

Fig. 2 is a fragmentary elevational view, partly in sec-` tion, of the apparatus shown in Fig. 1 illustrating .the orientation of the bulb with respect to the shield during the main portion of the spraying cycle and the last phase thereof;

Fig. 3 is a plan view of the apparatus shown in Fig. l; and

` Fig. 4 is an enlarged elevational view of a projection lamp incorporating a bulb of the type being processed in Figs. l,to 3, a top part of the bulb being broken away and in section to more clearly illustrate the character of the coating thereon.

Although the principles of this invention are broadly applicable to the selective treatment or coating of various types of articles having diverse shapes, the invention is especially suited for use in a spray type coating machine for applying an opaque layer of -nely-divided material to the tops of cylindrically hollow articles such as projection lamp bulbs and hence has been so illustrated and will be so described. Y

With specic reference now to the drawing, in Fig. 4 there is shown a conventional type incandescent` projection lamp 1t? comprising, in general, a tubular bulb 12 one end of which is closed to form a rounded end portion i and the other sealed to a re-entrant stem 1S and tted with a prefocus type base 14. In accordance with the usual construction employed in lamps of this character (a representative sample of which is shown and described in U.S. Patent No. 2,140,977), the re-entrant stem 18 axially projects into the bulb 12 and supports a pair of spaced longitudinally extending leads 19 and 20 between which a sectionally-coiled tungsten lament 21 (of either the well-known monoplane or biplane type) is supported by means of suitable top and bottom bridge assembli. The lamp 1) is designed to be burned in thebase down position shown in Fig. 4 so that the closed end of the bulb 12 constitutes the top portion of the lamp which portion, in accordance with the aforementioned practice, is provided with an opaque coating 16 of suitable high-temperature material such as ceramic paint or ,the like to intercept undesirable upward components of stray light emanating from `the lament 21. As will be obvious, it is highly desirable that the coating material be applied in such a manner that only a predetermined top portion h2 (see Figs. 2 and 4) Aof the bulb be coated and that the cut-ofi line be sharply dened, that is, substantially free from any raggedness or feathering, so that the coating as applied is of acceptable quality from an appearance standpoint without subjecting the bulb to a costly and time-consuming cleaning operation.

The essence of this invention resides in the method and means for masking la predetermined body portion of the bulb 12 during the spraying operation so that the cut-olf line is not only precisely located but free from appearance defects such as feathering or the like and these will be` hereinafter described.

- In Fig. 1 there is shown an apparatus for spray coating; a` selected top portion of a projection lamp bulb 12 acq cording to one embodiment ofthe present invention. 4The assembly 40 to thus enclose the body portion of the bulb and leave a selected top portion h1 thereof exposed for coating as by an atomized jet of timely-divided material from a suitable spray gun 74 well-known in the art.

In order to insure that the coating material is applied evenly, the bulb 12 is desirably rotated at a suitable speed during the coating operation. This may be conveniently accomplished by mounting the sheld 22 on a spacing ring 3 0 carried by a support tube 32 which is rotatably held by means of a thrust bearing 31 and bushings 33 and 35 in upstanding coaxial vrelation within a stationary housing 36 affixed to the frame 37 of the machine. Thus, when the support tube 32 is rotated in the direction shown in Fig. l, as by a well-known drive pulley 34 secured to the end ofthe tube, the shield 22,- bulb-supporting assembly 40 (a portion ofwhich is securedto the support tube 32), andthe bulb 12 seated thereon rotate as a unit. By virtue' of the 'foregoing construction, however, the bulbsupporting assembly 40 and bulbV 12 are reciprocably displaceabl with respect tothe shield 22 so that the bulb may be accurately positioned and controllably manipu lated therein by properly actuating the lower end of saidA as air into the interior of the shield 22, as contemplated by the preferredv embodiment of this invention shown in the drawing, the bulb-supporting assembly 40 is desirably fabricated in two sections, namely, an upper solid spindle 42 and alower hollowspindle 52 conjoined in coaxial relation to form an integral elongated member, the latter spindle constituting the lower portion of said assembly and'being slidably disposed within the support tube 32. The upper spindle 42 terminates in a collar 44 having three radially-spaced finger-likeelements 46 arranged (as shown in Figs. l and 2)v to provide a rigidly anchored spider assembly adapted when compressed inwardly by the bulb 12.to resiliently engage `and grip the interior wall surface of the bulb. Therupper spindle 42 is provided with a tip element 481 which is covered by a Vthimble-like cap 50 of suitable shock absorbing material such as rubber or the like to providea stop contoured to nest within the dome of the bulb 12 and accurately position the bulb on the supportinglassembly 40, as shown in Figs. 1 and The closedy end of the bulb 112 is thus used` as the reference point in determining' the line of cutoff, as hereinafter explained, so that equal segments of each of the bulbs are coated regardless of variations in the overall bulb 'length prior to the sealing-inoperation.

-The introduction of asitable gas such asair under pressure into the shield 22 may be conveniently accomplished for the purpose hereinafter disclosed by utilizing the lower hollow spindle'52 as a conduit by proportioning saids'pindle so asto project slightly beyond the upper edge of the support tube 32 and a predetermined distance beyond the lower edge thereof and the attached pulley 34, as viewed in Fig. l. The end of the lower spindle 52 which protrudes into the shield 22 is provided with a plurality of apertures 53 to eiect communication with the shield interior. The opposite end of the lower spindle 52 is closedby a set screw 70 and is provided with an aperture 55 which opens into a chamber 63 de- The chamber 63in turn, connects with a pressurized air supply (not shown) throughua llexible conduit 60 attached to a T-shaped nipple 58 carried by said bracket.

The bracket 62 is 'suitably forked or apertured (as shown in Fig. 1) to slidin'gly accommodate a'stud68f fastened to a horizontally disposed plate 66 secured to the frame 37 which stud is disposed in parallel relation with the airis of the support tube 32. Thus, the lower spindle 52 is 'anchored' in coaxial alignment with the supportr tube 32 permitting the bulb-supporting assembly 40 to move freely longitudinally with respect to said tube and the shield 22. The rate of flow of the air from the pressurized source into 'the shield 22 lmay be controlled in any convenient manner as by an adjustable reducing valve (not shown) in the conduit 60. Y

The plate 66 projects beyond the lower spindle 52 suiiciently to pnovide a stop for an appropriately located pin 54 carried by the lower spindle 52 which thus limits the downward travel of Vthe bulb-supporting assembly 40 and accurately positions the top portion'thereof with respect to the shield 22 so that when said pin and plate are seated one against the other, a bulb 12 disposed on said assembly will protrude a predetermined distance h1 (seeA Figs. land 2) beyond the edge Iof th shield 22. A helical spring 65 interposed between the plate 66 and the flange of the vretaining ring 56 maintains the pin 54 in firmly seated engagement with the plate 66 so that only a predetermined top portion h1 of the bulb 12 is exposed when the vbulb-supporting assembly 40 is in normally-recessed position within the shield y22. The set screw 70, in addition to sealing-off the end ofthe lower spindle 52., en-

ables the overall length of the bulb-supporting assembly 40 to be precisely adjusted so that when said set screw and assembly are urged upwardly by means of a suitablef lifting lever 72, asv shown by the dotted outline of said lever in Fig. 1, a bulb 12 when in loaded position on said assembly will be raised an additional predetermined distance out of the shield 22 and a proportionately longer section h2 [of the bulb top exposed, as shown in Fig. 2.

A setv screw 73 carried by the lever arm in combination withl an interposed spring'71 permits the distance the bulb. 12 ,is raised out ofthe shield 22 to be `accurately controlled andV maintains the lifting lever 72 normally disengaged. To facilitate unloading, the bulb 12 may be raisedeven further out of the shield 22 against the action ofthe spring 65 by means of a handle 59 secured to the T-shaped nipple 58 carriedwby the bracket 62.

In order to accommodate bulbs of Various standard' lengths, the shield 22 is desirably fabricated in two sections, astshownl in Figs. l` and y2, namely, a movable sleeve 24 andifa stationary sleeve 28 arranged intelescopic relation Yso as to vary/the overall length of the shield by adjusting :the position of a set screw 26l engageableV at' d ilerentpoints with apertures 27 in, the'movable sleeve. To minimize' the thus reduce the. incidence of leakage, so to speak, the free end of the movable 'sleeve 24 istapered inwardly to dene a4 centra. aperture which is only slightly greater inl diameter than the maximum outer diameter of the bulb 1.2 to be accommodatedA thus providing, when said bulb is in centrally-loaded position on the bulb-supportingt assembly 40, an` annular escapement or oonstricted opening 25 as shown in Figs. l, A2 and 3. As shown in Fig. `1, the movable sleeve 24 is of suicient length that when, the set screw 26 provided therein is disposed in the uppermostposition in the stationary sleeve 28, the lowermost of the screw-apertures 27 remains covered by the movable, sleeve .thereby lrendering the shield 22 substantiallyairtght. regardlessk of the size of the bulb being processed. Thus, whenL the bulb 12 is seated in loaded positionf on. they bulb-supporting assembly 40, the shield 22. in conjunction with the inner andr outer surfaces of the bulbfdefines an air tight chamber A open to the atmosphere andthe sprayed particles only through an annular.: salubridad. Opening; 2,5,w1aish1eneirsles the bulb v K number of sprayed. particles which impinge yon'the gap between the bulb 12 yand shield 22and liliv example 1A of an inch, out ofthe shield 22 ing thenecessary heat tov ing. process` to be completed while the bulb is still beingl on: a. diametric planek ata predetermined point. along; it` in Figs. 1 andY 2;. thereby longitudinal axis, 'asillustrated dening the line lof cut-off and exposing a predetermined length (either h1. or h2 depending on whether or' not the lifting lever 72V is actuated)` of the bulb top for processing.

' Operation In processing the bulb 12 in accordancewith. the prin-v coaxial and juxtaposedrelation with the shield (as illustrated in Figs. l to 3) to thus define the aforementioned. air tight chamber A and constricted opening 25. With the bulb 1 2 in this position a predetermined body portiony thereof, in excess of that desired to be shielded is en-Y closedleaving a length h1 of. the bulb` top exposed as above-described; The entire` assembly is then rotated at asuitable speed by the drive pulley 34 and clean dry air,

at a pressuresuiicient to iillthe chamber A and maintain, an outward tlow through the opening 25.during'the,coat-l-I ing operation', is fedffnom a suitablev pressurized source-v into, the, shield 2,2 by means of the above-mentioned conj nipple 58, and apertured lower spindle)` duit 60, T-shaped 52. t e ,"Ihespraygun 74; is then triggered and 'progressively swung alongfa diametric plane in-an arcuate path al from; a position slightlybelow the horizontal togone just short again" along the path a2 to.thus.,-

ofthe vertical andv .bacle .scant the exposed top portion h1 of the bulb 12,Y as shown the desired opacity is obtained.l

in Fg.- 1., until, @coating 0f After-the top portion of h1 ofthe bulb 12 hasjbeen coated in the foregoing manner and the spray gun- 74` has'been returnedto a position abreast oftor preferably as shownin,

slightly below the edge of the shield 22, Figs. 1 and 2, the lifting lever 72 is actuated and thebulbl 12 raised an additional predetermined distance, as for ay proportionally longer length h2 of the bulb top to pro.- trude` and expose the final cut-olf region, as illustrated in Fig.v 2. This bring the final cut-orf line into coincidingV relation with-the edge of the shield 22 and the opening.V 25` and extends the.l coating to the selected tnal. line of= cut-oit. By virtue ofthe recessed` position of the gun.

j 7 4 and ow from the opening 25, the main portion. of' the spray is deected'f-by the shield'22 andthe chamber.' A is Vsealedioi from4 thel turbulence or backwash` generated` Y by the spray thus sharply terminating the, coating` 16 (seef f Fig.4) ,y at the, nalflineofcutoffand'v'obviatingfanyf'- blunring, orv featheringf` effects.

After lthe coating `opera-v tion has; been completed and the coatingma-terialsu'fli'- centlyrset, the apparatus isbrought toa stop where-f upon the` bulb-'12is` raised further out `of -the'shield 22' 'Y Y 59 to permit the uncoatedv portion t l ofthe bulb tobe gripped and the bulb removed withoutv by means of thehandle smudging `or othenwise disturbing the coating. Theco'atf ing 16 is then cured as by baking inthe usual manner. It will, of course, 'be chamber A, in addition heated to accelerateV the setting-up of the coating maten'al at the line of cut-off or means provided for apply`Y the coating to permit the cur# rotated on the. machine. l

Alternatively, 4is usedand: the opening 25'is made as narrow as prac"-V ticable. and the. spray gun positioned Well below theedg oftheshield during the iinal thel overall length of the shield r` inserting the set screw 26 in the to thus cause,

obvious that the air fed into the to being clean and dry, may-bei experience has shown that if a soft sprayf s! phase of the spraying cyclef' -to minimize the incidence of rleakage, the injection offv air. into; the; shield: v22 `rnayrb'e eliminated withoutdelete= ri'ously aecting the quality of the `finished coating there'- by even further simplifying the apparatus and coating `operation.

After the coated bulb I12 has been removed, the handle 59 is released whereupon the bulb-supporting assembly 40 in response to the action of the spring 65 returns to its normally-recessed loading position and the foregoing cycle is repeated.

As will be apparent from the foregoing, the objects of the invention have been achieved by providing a method and means for masking a preselected body portion of an article from a pressure-applied processing medium and eiecting in a simple and inexpensive manner a sharp and neatly-defined line of cut-off free from feathering or other appearance defects. In addition, by utilizing a loose-fitting shield yof rigid construction in combination with a simple actuating mechanism for precisely controlling the relative position of the loaded article and the shield during the treating cycle and effecting the desired final line of cut-ofi, the masking apparatus is not only made inherently trouble-free and durable but convenient and simple to operate thereby rendering it especially suited for use in automated equipment.

While the present invention has been described in some detail by way of illustration and assembly for purposes of clarity and understanding in accordance with the patent statutes, it is understood that various changes and modifications may be made without departing from the spirit and scope of the invention.

I claim:

1. The method of masking a selected .body portion of an article from a processing medium sprayed from ai movable source which scans the exposed end portion of said article, and effecting a desired final line of cut-off which method comprises, inserting said article into a shielding member adapted to loosely receive the selected body portion tol be protected and define therewith a chamber open to the atmosphere and normally accessible to said processing medium through a constricted opening which, in turn, defines the line of cut-off on said article, positioning said article so that a predetermined part thereof in excess of the said selected body portion to be protected is recessed below the edge of said shielding member `while said medium source scans the exposed end portion of said article, placing said medium source abreast of and preferentially below the deiining'edge of said shielding member and constricted opening thereat after the aforesaid end portion has been processed, and then raising said article an additional distance out of said shielding member to expose the recessed predetermined part of said article which is in excess of the said selected body portion and thereby eifect said desired final line of cut-off. i

2. The method of masking a selected body portion of a cylindrical article from a processing medium sprayed from a movable source which scans the exposed end portion of said article and effecting a desired final line of cut-off which method comprises, inserting said article into anapertured shielding member adapted to loosely receive the selected body portion to be protected and define therewith a chamber open to the atmosphere and normally accessible to said processing medium through a constricted opening which, in turn, defines the line of cut-off on said article, introducing into said chamber a pressurized gas at a rate sufficient to maintain from said opening an outward iiow such that the turbulentcurrents generated by said processing medium are prevented from entering said opening and chamber, positioning said article so that a predetermined part thereof in excess of the said selected body portion to be protected is recessed within said shielding member while said medium source scans the exposed end portion of said article, placing said medium source abreast of and preferentially below the defining edge of said shielding member and constricted opening thereat after the aforesaid end portion has been processed, and

then raising'said article out of said shielding member an additional distance sutiicient to expose the recessed predetermined part of said article which is in excess of the said selected body portion and thereby effect said desired nal line of cut-off.

3. The method of masking a selected body portion of an article from a stream of sprayed processing ma terial and effecting a desired final line of cut-off which method comprises, inserting said article into an apertured shielding member adapted to loosely receive and contain the selected body portion of said article, positioning said article within said shielding member to define with the encircling edge thereof a relatively narrow opening and dispose a predetermined line of cut-off on said article in slightly recessed relation with respect to said edge, rotating said article and shielding member while so positioned, and, after the exposed end portion of said article has been sprayed, positioning the source of said sprayed material laterally of and preferentially below the encircling edge of said shielding member and aligning said predetermined line of cut-oi on said article with the aforesaid edge and opening to eiiect said desired iinal line of cut-off.

4. The method of masking a selected body portion of an ar-ticle from a stream of sprayed processing material and effecting a desired final line of cut-ofi which method comprises, inserting said article into an apertured shielding surface adapted to loosely receive the selected body portion of said article and define a predetermined line of cut-off on said article, positioning said article relative to said shielding surface so that a predetermined part of said article in excess of the said selected body portion to be masked is recessed, coating the exposed end portion of said article with said sprayed processing material, aiming the stream of sprayed material toward the exposed end of said article from a point below the said predetermined line of cut-off, and then producing relative movement between said article and shielding surface to expose to said sprayed material the recessed predetermined part of said article which is in excess of the selected body portion to be masked and thereby effect said desired final line of cut-off.

5. Apparatus for masking a selected body portion of an article from a sprayed processing medium comprising, a masking member adapted to loosely encircle said selected body portion of said article and having an opening adapted to expose the end portion of said article to be processed, the edge of said masking member at said opening being of such configuration as to define with the encircled part of said article a relatively narrow passage when said article is in its inserted position, means for providing a flow of gas through said passage to substantially prevent the inux of said processing medinm'into said passage, and means for producing relative movement between said article and masking member such that a predetermined line of cut-off on said article is first recessed with respect to the defining edge of said masking member and then disposed in coinciding relation therewith.

6. Apparatus for masking a selected body portion of an article from a sprayed processing medium comprising, an apertured shielding member dimensioned to loosely receive a part of said article in excess of the aforesaid selected body portion to be protected and contoured to define therewith a chamber with an opening to the atmosphere and normally accessible to said processing medium, means for accurately positioning said article Within said shielding member so that the opening defined by said article and shielding member coincides with a predetermined final line of cut-off on said article, and means for producing relative movement between said article and said shielding member and a resultant displacement there of suiicient to align the aforesaid final line of cut-off on said article with said opening from a normally re- Aceased position.

17. Apparatus for masking a selected body portion of a cylindrical article from a sprayed processing medium comprising a centrally-apertured shielding member dimensioned to loosely receive a part of said article in excess of the aforesaid selected body portion to be protected and contoured to define therewith a chamber with a constricted opening to the atmosphere and normally accessible to said processing medium-means for supporting said article within said shielding member so that the constricted opening thus defined is normally disposed a predetermined distance beyond a preselected line of cut-oit on said article toward the exposed end thereof, and means for raising the article said predetermined distance out of said shielding member to bring the aforesaid preselected line of cut-ott on said article into coinciding relation with said constricted opening.

8. Apparatus for masking a selected body portionrof a cylindrically hollow article such as a tubular lamp bulb from a stream of sprayed particles comprising a centrallyapertured shield of cylindrical configuration dimensioned to loosely contain a part of saidparticle in excess ofthe body portion to be protectedwanrd contoured tordene therewith a chamber with aj constrictd openingtothe f atmosphere and normally accessible to said processing medium, means for supporting said article within said shield so that the constricted opening thus defined normal'` i ly encircles said article at a point spaced a predetermined Y ReferenceSVCited inthe file of this patent v UNITED STATES' PATENTS 2,151,427 Blinden...l Mar. 21, 1939 y2,242,032 Houk May. 13, 1941 v2,342,375 Shurley'ni.; A.. Feb. 272, 1944 2,600,161 Fouse '-n-.. June l0, 19521 V2,781,282 Morgan et*V l. a Feb. 12,1957r `I-Iill 

1. THE METHOD OF MASKING A SELECTED BODY PORTION OF AN ARTICLE FROM A PRCESSING MEDIUM SPRAYED FROM A MOVABLE SOURCE WHICH SCANS THE EXPOSED END PORTION OF SAID ARTICLE, AND EFFECTING A DESIRED FINAL LINE OF CUT-OFF WHICH METHOD COMPRISES, INSERTING SAID ARTICLE INTO A SHIELDING MEMBER ADAPTED TO LOOSELY RECEIVE THE SELECTED BODY PORTION TO BE PROTECTED AND DEFINE THERWITH A CHAMBER OPEN TO THE ATMOSPHERE AND NORMALLY ACCESSIBLE TO SAID PROCESSING MEDIUM THROUGH A CONSTRICTED OPENING WHICH, IN TURN, DEFINES THE LINE OF CUT-OFF ON SAID ARTICLE, POSITIONING SAID ARTICLE SO THAT A PREDETERMINED PART THEREOF IN EXCESS OF THE SAID SELECTED BODY PORTION TO BE PROTECTED IS RECESSED BELOW THE EDGE OF SAID SHIELDING MEMBER WHILE SAID MEDIUM SOURCE SCANS THE EXPOSED END PORTION OF SAID ARTICLE, PLACING SAID MEDIUM SOURCE ABREAST OF AND PREFERENTIALLY BELOW THE DEFINING EDGE OF SAID SHIELDING MEMBER AND CONSTRICTED OPENING THEREAT AFTER THE AFORESAID END PORTION HAS BEEN PROCESSED, AND THEN RAISING SAID ARTICLE AN ADDITIONAL DISTANCE OUT OF SAID SHIELDING MEMBER TO EXPOSE THE RECESSED PREDETERMINED PART OF SAID ARTICLE WHICH IS IN EXCESS OF THE SAID SELECTED BODY PORTION AND THEREBY EFFECT SAID DESIRED FINAL LINE OF CUT-OFF. 